![]() ![]() When it was all over, it left behind a 90-degree turn in the river we know today as the Whirlpool, and North America’s largest series of standing waves we know today as the Whirlpool Rapids. It was probably not a falls at all now but a huge, churning rapids. The falls turned into this buried gorge, tore out the glacial debris that filled it, and scoured the old river bottom clean. In this moment, the falls of the youthful Niagara River intersected an old riverbed, one that had been buried and sealed during the last Ice Age. ![]() It was a brief and violent encounter: a geological moment lasting only weeks, maybe even only days. For the next 5,000 years, Lake Erie remained only half the size of today, the Niagara River was reduced to about 10 percent of its current flow, and a much-reduced falls stalled in the area of the Niagara Glen.Ībout 5,500 years ago, the melt waters were once again routed through Southern Ontario, restoring the river and falls to their full power. The glacial melt waters were rerouted through Northern Ontario, bypassing the southern route. However, about 10,500 years ago, through an interplay of geological effects including alternating retreats and re-advances of the ice, and rebounding of the land when released from the intense pressure of the ice (isostatic rebound), this process was interrupted. From here, the falls began its steady erosion through the bedrock. Eventually, these were reduced to one, the original Niagara Falls, at the escarpment at Queenston-Lewiston. There were originally five spillways from Lake Erie to Lake Ontario. Lawrence River and on to the Atlantic Ocean. As the ice retreated northward, its melt waters began to flow down through what became Lake Erie, the Niagara River and Lake Ontario, down to the St. The Niagara Peninsula became free of the ice about 12,500 years ago. Our water is “fossil water.” Less than one percent of it is renewable on an annual basis, the rest leftover from the ice sheets. ![]() Then as they melted northward for the last time, they released vast quantities of melt water into these basins. As the ice sheets advanced southward, they gouged out the basins of the Great Lakes. 18,000 years ago, Southern Ontario was covered by ice sheets two to three kilometres thick. The Niagara River, and the entire Great Lakes Basin of which it is a part, is a legacy of the last Ice Age. To convert from tonnes per second to tonnes per hour, multiply by 3,600. To convert from tonnes per second to tonnes per minute, multiply by 60. The “non-tourist flow” of 50,000 cfs converts to 1,416 cms, which means that 1,416 tonnes of water per second is flowing over the falls.During the high season, the “tourist flow” over the falls of 100,000 cubic feet per second (cfs) converts to 2,832 cubic metres per second (cms), meaning 2,832 tonnes of water per second is flowing over the falls.We can disregard temperature and pressure for this calculation, although you should be aware that the mass of water decreases as the temperature rises and/or the pressure decreases. STP is the weight of water at zero degrees centigrade at seas level, which is one atmosphere (atm) of pressure. In this case, we are referring to water, which at standard temperature and pressure (STP) weighs one tonne per cubic metre. So, how much water actually flows over Niagara Falls? First, the term “tonnes” refers to a metric tonne, also known as a long ton. Niagara Falls has moved back seven miles in 12,500 years and may be the fastest moving waterfalls in the world.The Niagara River is a connecting channel between two Great Lakes, Erie and Ontario.The rapids above the falls reach a maximum speed of 40 km/hr or 25 mph, with the fastest speeds occur at the falls themselves (recorded up to 68 mph.) The water through the Whirlpool Rapids below the falls reaches 48 km/hr or 30 mph, and at Devil’s Hole Rapids 36km/hr.The crest line of the American Falls is approximately 260 metres (850 ft.) wide The height of the falls from the top of the falls to the river is 57 metres (188 ft.). This measurement is taken from the top of the falls to the top of the rock pile at the base, called the talus slope. The height of the American Falls ranges between 21 to 34 metres (70-110 ft.).The plunge pool beneath the falls is 35 metres (100 ft.) deep The crest line of the Canadian Horseshoe Falls is approximately 670 metres (2,200 ft.) wide. ![]() The Canadian Horseshoe Falls drops an average of 57 metres (188 ft.) into the Lower Niagara River.More than 168,000 cubic metres (6 million cubic ft.) of water go over the crestline of the falls every minute during peak daytime tourist hours. ![]()
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |